1. Field of the Invention
The invention relates to a method for manufacturing a tube-like extrusion profile with a desired combination of properties, in particular with regard to flexibility, torsional stiffness and pressure resistance. More specifically, the present invention relates to the extrusion of a tube with helically extending bands of other material than the base material of the tube. These helically extending bands can be of harder material so that the stiffness properties of the tube can be improved and by using two helical bands with opposed directions, a substitute for braided reinforcement is obtained.
2. Description of the Prior Art
Catheters used for angiographic purposes, for instance, comprise a tube-like basic body which must have a good torsional stiffness in order to be able to manipulate the catheter properly. Furthermore, this material should have a high compression resistance to allow, for example, the introduction of contrast medium under high pressure via the catheter.
The usual catheters of this type, therefore, comprise a braided reinforcing layer of metal wire, providing the required properties.
With the continuing trend towards ever thinner catheters, it is becoming increasingly difficult and expensive to manufacture a suitable tube-like basic material in this way.
Heretofore various wire reinforced catheters and methods for making same have been proposed and analogous and nonanalogous examples of some of these tubular body constructions, e.g., catheters, and methods for making same are disclosed in the following U.S. Patents and foreign patent publications:
______________________________________ U.S. Pat. No. Patentee ______________________________________ 2,779,970 Stocker 3,606,636 Glass et al. 3,426,744 Ball 3,618,613 Schulte 3,752,617 Burlis et al. 4,044,765 Kline 4,050,411 Kimmich 4,073,287 Bradely et al. 4,176,662 Frazer 4,276,250 Satchell et al. 4,665,604 Dubowik 4,705,511 Kocak 4,776,334 Prionas 4,840,186 Lekholm et al. 4,945,342 Steinemann 4,947,866 Lessar et al. 5,112,304 Barlow et al. 5,324,275 Raad et al. 5,279,596 Castenada et al. ______________________________________
British Published Patent Application
UK Patent Appl. No. 1,349,843 to Creators Ltd.
UK Patent Appl. No. 2,218,580 to Nogami et al.
EP Published Patent Application
EP Pub. No. 0 249 338 to Spector et al
French Patents
French Patent No. 1,555,590 to Labarre et al.
French Patent No. 2,649,642 to Figuere et al.
German Patent Publications
DE 19 38 720 (Offenlegungsshrift) to Kalwar
Swiss Patents
Swiss Patent No. 279,074 to Datwyler